Ceramic materials are well known and widely used for different applications due to some of their exceptional properties such as high modulus, hardness, high temperature stability and chemical resistance. However they are also heavy, brittle, and difficult to process. On the other hand, organic polymers are tough, flexible, light, and easy to fabricate; low modulus and relatively low decomposition temperatures are their main drawbacks. Pre-ceramic polymer technology is emerging as a promising process to produce materials that share the advantages of both polymers and ceramics while minimizing the disadvantages.
Furthermore new methods are needed to create micron-size (or even smaller) ceramic structures for applications such as microelectronics and microelectromechanical systems (MEMS). A particularly challenging area is creating three-dimensional (3D) ceramic structures. These application areas are very difficult using traditional ceramic technologies. Pre-ceramic polymers afford unique properties in responding to these requirements.
Many polymers such as polysilazanes are known to act as ceramic precursors and their use for production of ceramic structures has been reported. The formation of miniaturized ceramic structures by pyrolysis of poly (vinylsilazane) using LIGA (German Lithographie, Galvanoformung, and Abformung) process including deep X-ray lithography, electroforming, and plastic molding has been demonstrated. An injectable polymer-precursor technique has been detailed; also a microforged mold method to fabricate high temperature MEMS using polysilazanes has been disclosed. All of the described techniques, however, involve complex and time-consuming processing.
Photopolymerization provides an alternative route to construct solid microstructures. Photopolymerization techniques offer direct pattern formation capability, freestanding structures, and cost-effective processing. Through layer-by-layer processes, such as stereolithography, photopolymerization techniques can also allow for the fabrication of 3-dimensional structures. Efforts have been made to create ceramic microstructures using free radical initiated photopolymerization of liquid polysilazane; low photopolymerization speed, however, was observed.
Single photon polymerization techniques have been used to form patterned pre-ceramic polymer microstructures using thiol-ene chemistry including polysilazanes. Two-photon polymerization of polymer nanocomposites has been used to pattern 3D silica microstructures.